The acute respiratory distress syndrome following isolated severe traumatic brain injury

Extracranial Complications in Monitored and Nonmonitored Patients with Traumatic Brain Injury in the BEST TRIP Trial and a Companion Observational Cohort

INTRODUCTION

Extracranial complications occur commonly in patients with traumatic brain injury (TBI) and can have implications for patient outcome. Patient-specific risk factors for developing these complications are not well studied, particularly in low and middle-income countries (LMIC). The study objective was to determine patient-specific risk factors for development of extracranial complications in TBI.

METHODS

We assessed the relationship between patient demographic and injury factors and incidence of extracranial complications using data collected September 2008-October 2011 from the BEST TRIP trial, a randomized controlled trial assessing TBI management protocolized on intracranial pressure (ICP) monitoring versus imaging and clinical exam, and a companion observational patient cohort.

RESULTS

Extracranial infections (55%), respiratory complications (19%), hyponatremia (27%), hypernatremia (27%), hospital acquired pressure ulcers (6%), coagulopathy (9%), cardiac arrest (10%), and shock (5%) occurred at a rate of ≥5% in our study population; overall combined rate of these complications was 82.3%. Tracheostomy in the intensive care unit (P < 0.001), tracheostomy timing (P = 0.025), mannitol and hypertonic saline doses (P < 0.001), brain-specific therapy days and brain-specific therapy intensity (P < 0.001), extracranial surgery (P < 0.001), and neuroworsening with pupil asymmetry (P = 0.038) were all significantly related to the development of one of these complications by univariable analysis. Multivariable analysis revealed ICP monitor use and brain-specific therapy intensity to be the most common factors associated with individual complications.

CONCLUSIONS

Extracranial complications are common following TBI. ICP monitoring and treatment are related to extra-cranial complications. This supports the need for reassessing the risk-benefit balance of our current management approaches in the interest of improving outcome.

Plumbagin ameliorates LPS-induced acute lung injury by regulating PI3K/AKT/mTOR and Keap1-Nrf2/HO-1 signalling pathways

Acute lung injury (ALI) is a major pathophysiological problem characterized by severe inflammation, resulting in high morbidity and mortality. Plumbagin (PL), a major bioactive constituent extracted from the traditional Chinese herb Plumbago zeylanica, has been shown to possess anti-inflammatory and antioxidant pharmacological activities. However, its protective effect on ALI has not been extensively studied. The objective of this study was to investigate the protective effect of PL against ALI induced by LPS and to elucidate its possible mechanisms both in vivo and in vitro. PL treatment significantly inhibited pathological injury, MPO activity, and the wet/dry ratio in lung tissues, and decreased the levels of inflammatory cells and inflammatory cytokines TNF-α, IL-1β, IL-6 in BALF induced by LPS. In addition, PL inhibited the activation of the PI3K/AKT/mTOR signalling pathway, increased the activity of antioxidant enzymes CAT, SOD, GSH and activated the Keap1/Nrf2/HO-1 signalling pathway during ALI induced by LPS. To further assess the association between the inhibitory effects of PL on ALI and the PI3K/AKT/mTOR and Keap1/Nrf2/HO-1 signalling, we pretreated RAW264.7 cells with 740Y-P and ML385. The results showed that the activation of PI3K/AKT/mTOR signalling reversed the protective effect of PL on inflammatory response induced by LPS. Moreover, the inhibitory effects of PL on the production of inflammatory cytokines induced by LPS also inhibited by downregulating Keap1/Nrf2/HO-1 signalling. In conclusion, the results indicate that the PL ameliorate LPS-induced ALI by regulating the PI3K/AKT/mTOR and Keap1-Nrf2/HO-1 signalling, which may provide a novel therapeutic perspective for PL in inhibiting ALI.

Prevalence, predictors, and outcomes of acute respiratory distress syndrome in severe stroke

OBJECTIVES

Patients with severe stroke are at high risk of developing acute respiratory distress syndrome (ARDS), but this severe complication was often under-diagnosed and rarely explored in stroke patients. We aimed to investigate the prevalence, early predictors, and outcomes of ARDS in severe stroke.

METHODS

This prospective study included consecutive patients admitted to neurological intensive care unit (neuro-ICU) with severe stroke, including acute ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. The incidence of ARDS was examined, and baseline characteristics and severity scores on admission were investigated as potential early predictors for ARDS. The in-hospital mortality, length of neuro-ICU stay, the total cost in neuro-ICU, and neurological functions at 90 days were explored.

RESULTS

Of 140 patients included, 35 (25.0%) developed ARDS. Over 90% of ARDS cases occurred within 1 week of admission. Procalcitonin (OR 1.310 95% CI 1.005-1.707, P = 0.046) and PaO2/FiO2 on admission (OR 0.986, 95% CI 0.979-0.993, P < 0.001) were independently associated with ARDS, and high brain natriuretic peptide (OR 0.994, 95% CI 0.989-0.998, P = 0.003) was a red flag biomarker warning that the respiratory symptoms may be caused by cardiac failure rather than ARDS. ARDS patients had longer stays and higher expenses in neuro-ICU. Among patients with ARDS, 25 (62.5%) were moderate or severe ARDS. All the patients with moderate to severe ARDS had an unfavorable outcome at 90 days.

CONCLUSIONS

ARDS is common in patients with severe stroke, with most cases occurring in the first week of admission. Procalcitonin and PaO2/FiO2 on admission are early predictors of ARDS. ARDS worsens both short-term and long-term outcomes. The conflict in respiratory support strategies between ARDS and severe stroke needs to be further studied.

Health-related quality of life measures in patients undergoing decompressive craniectomy for severe traumatic brain injury: a 6-year follow-up analysis

PURPOSE

We aimed to assess the long-term neurological outcomes and the functionality and QoL in patients undergoing decompressive craniectomy for severe traumatic brain injury, respectively.

MATERIALS AND METHODS

Among the 120 patients who underwent decompressive craniectomy for severe TBI between 2002 and 2007, 101 were included based on the inclusion criteria. Long-term follow-up results (minimum 3 years) were available for 22 patients. The outcomes were assessed using the Glasgow Outcome Scale (GOS) and the functionality and HRQoL were assessed using the Short Form-36 (SF-36) (v2) and Quality of Life After Brain Injury (QoLIBRI) questionnaires.

RESULTS

Among the patients with severe TBI, 62 (61.4%) died and 39 (38.6%) were discharged to either home or a physical therapy facility. Eleven of the thirty-nine patients could not be reached and were excluded from the final analysis. The mean GOS of the remaining 28 patients was 4.14 ± 0.8 after 6.46 ± 1.64 years of follow-up. The HRQoL was assessed in 22 of the 28 patients. The HRQoL scores were lower in patients with TBI than in healthy controls. Furthermore, there was a significant difference in the HRQoL scores in patients with improved GOS scores than in those with unimproved GOS scores.

CONCLUSIONS

Health-related outcome scores could help clinicians understand the requirements of survivors of severe TBI to create a realistic rehabilitation target for them. QoLIBRI served as a good way of communication in these subjects.

Incidence and Outcomes of Acute Respiratory Distress Syndrome in Brain-Injured Patients Receiving Invasive Ventilation: A Secondary Analysis of the ENIO Study

Background: Acute respiratory distress syndrome (ARDS) is an important pulmonary complication in brain-injured patients receiving invasive mechanical ventilation (IMV). We aimed to evaluate the incidence and association between ARDS and clinical outcomes in patients with different forms of acute brain injury requiring IMV in the intensive care unit (ICU). Methods: This was a preplanned secondary analysis of a prospective, multicenter, international cohort study (NCT03400904). We included brain-injured patients receiving IMV for ≥ 24 h. ARDS was the main exposure of interest and was identified during index ICU admission using the Berlin definition. We examined the incidence and adjusted association of ARDS with ICU mortality, ICU length of stay, duration of IMV, and extubation failure. Outcomes were evaluated using mixed-effect logistic regression and cause-specific Cox proportional hazards models. Results: 1492 patients from 67 hospitals and 16 countries were included in the analysis, of whom 137 individuals developed ARDS (9.2% of overall cohort). Across countries, the median ARDS incidence was 5.1% (interquartile range [IQR] 0-10; range 0-27.3). ARDS was associated with increased ICU mortality (adjusted odds ratio (OR) 2.66; 95% confidence interval [CI], 1.29-5.48), longer ICU length of stay (adjusted hazard ratio [HR] 0.59; 95% CI, 0.48-0.73), and longer duration of IMV (adjusted HR 0.54; 95% CI, 0.44-0.67). The association between ARDS and extubation failure approached statistical significance (adjusted HR 1.48; 95% CI 0.99-2.21). Higher ARDS severity was associated with incrementally longer ICU length of stay and longer cumulative duration of IMV. Findings remained robust in a sensitivity analysis evaluating the magnitude of unmeasured confounding. Conclusions: In this cohort of acutely brain-injured patients, the incidence of ARDS was similar to that reported in other mixed cohorts of critically ill patients. Development of ARDS was associated with worse outcomes.

Factors associated with acute respiratory distress syndrome in brain-injured patients: A systematic review and meta-analysis

PURPOSE

Acute respiratory distress syndrome (ARDS) is common in patients with acute brain injury admitted to the ICU. We aimed to identify factors associated with ARDS in this population.

METHODS

We searched MEDLINE, Embase, Cochrane Central, Scopus, and Web of Science from inception to January 14, 2022. Three reviewers independently screened articles and selected English-language studies reporting risk factors for ARDS in brain-injured adult patients. Data were extracted on ARDS incidence, adjusted and unadjusted risk factors, and clinical outcomes. Risk of bias was reported using the Quality in Prognostic Studies tool. Certainty of evidence was assessed using GRADE.

RESULTS

We selected 23 studies involving 6,961,284 patients with acute brain injury. The pooled cumulative incidence of ARDS after brain injury was 17.0% (95%CI 10.7-25.8). In adjusted analysis, factors associated with ARDS included sepsis (odds ratio (OR) 4.38, 95%CI 2.37-8.10; high certainty), history of hypertension (OR 3.11, 95%CI 2.31-4.19; high certainty), pneumonia (OR 2.69, 95%CI 2.35-3.10; high certainty), acute kidney injury (OR 1.44, 95%CI 1.30-1.59; moderate certainty), admission hypoxemia (OR 1.67, 95%CI 1.29-2.17; moderate certainty), male sex (OR 1.30, 95%CI 1.06-1.58; moderate certainty), and chronic obstructive pulmonary disease (OR 1.27, 95%CI 1.13-1.44; moderate certainty). Development of ARDS was independently associated with increased odds of in-hospital mortality (OR 3.12, 95% CI 1.39-7.00).

CONCLUSIONS

Multiple risk factors are associated with ARDS in brain-injured patients. These findings could be used to develop prognostic models for ARDS or as prognostic enrichment strategies for patient enrolment in future clinical trials.

Prediction of Acute Respiratory Distress Syndrome in Traumatic Brain Injury Patients Based on Machine Learning Algorithms

Background: Acute respiratory distress syndrome (ARDS) commonly develops in traumatic brain injury (TBI) patients and is a risk factor for poor prognosis. We designed this study to evaluate the performance of several machine learning algorithms for predicting ARDS in TBI patients. Methods: TBI patients from the Medical Information Mart for Intensive Care-III (MIMIC-III) database were eligible for this study. ARDS was identified according to the Berlin definition. Included TBI patients were divided into the training cohort and the validation cohort with a ratio of 7:3. Several machine learning algorithms were utilized to develop predictive models with five-fold cross validation for ARDS including extreme gradient boosting, light gradient boosting machine, Random Forest, adaptive boosting, complement naïve Bayes, and support vector machine. The performance of machine learning algorithms were evaluated by the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, accuracy and F score. Results: 649 TBI patients from the MIMIC-III database were included with an ARDS incidence of 49.5%. The random forest performed the best in predicting ARDS in the training cohort with an AUC of 1.000. The XGBoost and AdaBoost ranked the second and the third with an AUC of 0.989 and 0.815 in the training cohort. The random forest still performed the best in predicting ARDS in the validation cohort with an AUC of 0.652. AdaBoost and XGBoost ranked the second and the third with an AUC of 0.631 and 0.620 in the validation cohort. Several mutual top features in the random forest and AdaBoost were discovered including age, initial systolic blood pressure and heart rate, Abbreviated Injury Score chest, white blood cells, platelets, and international normalized ratio. Conclusions: The random forest and AdaBoost based models have stable and good performance for predicting ARDS in TBI patients. These models could help clinicians to evaluate the risk of ARDS in early stages after TBI and consequently adjust treatment decisions.

Platelet Transfusion for Trauma Resuscitation

Purpose of Review

To review the role of platelet transfusion in resuscitation for trauma, including normal platelet function and alterations in behavior following trauma, blood product transfusion ratios and the impact of platelet transfusion on platelet function, platelet function assays, risks of platelet transfusion and considerations for platelet storage, and potential adjunct therapies and synthetic platelets.

Recent Findings

Platelets are a critical component of clot formation and breakdown following injury, and in addition to these hemostatic properties, have a complex role in vascular homeostasis, inflammation, and immune function. Evidence supports that platelets are activated following trauma with several upregulated functions, but under conditions of severe injury and shock are found to be impaired in their hemostatic behaviors. Platelets should be transfused in balanced ratios with red blood cells and plasma during initial trauma resuscitation as this portends improved outcomes including survival. Multiple coagulation assays can be used for goal-directed resuscitation for traumatic hemorrhage; however, these assays each have drawbacks in terms of their ability to measure platelet function. While resuscitation with balanced transfusion ratios is supported by the literature, platelet transfusion carries its own risks such as bacterial infection and lung injury. Platelet supply is also limited, with resource-intensive storage requirements, making exploration of longer-term storage options and novel platelet-based therapeutics attractive. Future focus on a deeper understanding of the biology of platelets following trauma, and on optimization of novel platelet-based therapeutics to maintain hemostatic effects while improving availability should be pursued.

Summary

While platelet function is altered following trauma, platelets should be transfused in balanced ratios during initial resuscitation. Severe injury and shock can impair platelet function, which can persist for several days following the initial trauma. Assays to guide resuscitation following the initial period as well as storage techniques to extend platelet shelf life are important areas of investigation.

The Connection Between Selected Caspases Levels in Bronchoalveolar Lavage Fluid and Severity After Brain Injury

Objective

The interaction between the brain and lungs has been the subject of many clinical reports, while the exact impact of brain injury on the physiology of the respiratory system is still subject to numerous experimental studies. The purpose of this study was to investigate the activation of selected caspases levels in bronchoalveolar lavage fluid (mini BALF) of patients after isolated brain injury and their correlation with the severity of the injury.

Methods

The analysis was performed on patients who were admitted to the intensive care unit (ICU) for severe isolated brain injury from March 2018 to April 2020. All patients were intubated and mechanically ventilated. Mini BALF was collected within the first 6–8 h after trauma and on days 3 and 7 after admission. The concentrations of selected caspases were determined and correlated with the severity of brain injury evaluated by the Rotterdam CT Score, Glasgow Coma Score, and 28-day mortality.

Results

Our results showed significantly elevated levels of selected caspases on days 3 and 7 after brain injury, and revealed apoptosis activation during the first 7 days after brain trauma. We found a significant different correlation between the elevation of selected caspases 3, 6, 8, and 9, and the Glasgow Coma Score, Rotterdam CT scale, and 28-day mortality.

Conclusions

The increased levels of selected caspases in the mini BALF in our patients indicate an intensified activation of apoptosis in the lungs, which is related to brain injury itself via various apoptotic pathways and correlates with the severity of brain injury.

Molecular hydrogen alleviates lung injury after traumatic brain injury: Pyroptosis and apoptosis

BACKGROUND

Traumatic brain injury (TBI)-induced acute lung injury (ALI) is a critical condition, and inflammation and apoptosis play essential roles. Molecular hydrogen (H₂) exerts anti-inflammatory and anti-apoptotic effects. Our previous work has shown that 42% H₂ can improve TBI. In the current study, we tested the hypothesis that inhalation of hydrogen (42% H₂, 21% O₂, balanced nitrogen) for 1 h per day can improve TBI-induced ALI.

METHODS

Sprague-Dawley male rats were randomly divided into 3 groups. Except for the sham group (group S), rats were subjected to a fluid percussion injury (FPI) and the H₂ treatment group were given inhaled hydrogen for 1 h per day. We evaluated the lung function, pyroptosis and apoptosis at 24 h, 48 h and 72 h.

RESULTS

Compared with group S, the rats in the TBI group (group T) showed obvious pulmonary edema after a TBI. Inhalation of high-concentration hydrogen significantly improved the rats. During this process, rats had some tendency to heal on their own, and H₂ also accelerated the self-healing process. Lung injury scores, oxygenation index and pulmonary edema were consistent. Compared with group S, the pyroptosis-related proteins Caspase-1, apoptosis-associated speck-like protein containing CARD (ASC) and Gasdermin-D (GSDM-D) in the lung tissues of the rats in group T were significantly increased after a TBI. In the H₂ treatment group (group H), these proteins were significantly decreased. The levels of IL-1β and IL-18 were significantly increased after TBI while in group H were significantly decreased. At the same time, cleaved caspase-3 and BCL-2/Bax were also changed after H₂ treatment. These demonstrates the powerful ameliorating effect of H₂ on pyroptosis, apoptosis and systemic inflammation. However, rats also had tendency to heal on their own, and H₂ also accelerated the self-healing process at the same time.

CONCLUSIONS

H₂ improves TBI-ALI, and the mechanism may be due to the decrease of both pyroptosis and apoptosis and the alleviation of inflammation. These findings provide a reference and evidence for the use of H₂ in TBI-ALI patients in the intensive care unit (ICU).

Controversies and evidence gaps in the early management of severe traumatic brain injury: back to the ABCs

Traumatic brain injury (TBI) accounts for around 30% of all trauma-related deaths. Over the past 40 years, TBI has remained a major cause of mortality after trauma. The primary injury caused by the injurious mechanical force leads to irreversible damage to brain tissue. The potentially preventable secondary injury can be accentuated by addressing systemic insults. Early recognition and prompt intervention are integral to achieve better outcomes. Consequently, surgeons still need to be aware of the basic yet integral emergency management strategies for severe TBI (sTBI). In this narrative review, we outlined some of the controversies in the early care of sTBI that have not been settled by the publication of the Brain Trauma Foundation’s 4th edition guidelines in 2017. The topics covered included the following: mode of prehospital transport, maintaining airway patency while securing the cervical spine, achieving adequate ventilation, and optimizing circulatory physiology. We discuss fluid resuscitation and blood product transfusion as components of improving circulatory mechanics and oxygen delivery to injured brain tissue. An outline of evidence-based antiplatelet and anticoagulant reversal strategies is discussed in the review. In addition, the current evidence as well as the evidence gaps for using tranexamic acid in sTBI are briefly reviewed. A brief note on the controversial emergency surgical interventions for sTBI is included. Clinicians should be aware of the latest evidence for sTBI. Periods between different editions of guidelines can have an abundance of new literature that can influence patient care. The recent advances included in this review should be considered both for formulating future guidelines for the management of sTBI and for designing future clinical studies in domains with clinical equipoise.

17α-Ethinyl estradiol-3-sulfate increases survival and hemodynamic functioning in a large animal model of combined traumatic brain injury and hemorrhagic shock: a randomized control trial

Background

Traumatic brain injury (TBI) and severe blood loss resulting in hemorrhagic shock (HS) represent leading causes of trauma-induced mortality, especially when co-occurring in pre-hospital settings where standard therapies are not readily available. The primary objective of this study was to determine if 17α-ethinyl estradiol-3-sulfate (EE-3-SO4) increases survival, promotes more rapid cardiovascular recovery, or confers neuroprotection relative to Placebo following TBI + HS.

Methods

All methods were approved by required regulatory agencies prior to study initiation. In this fully randomized, blinded preclinical study, eighty (50% females) sexually mature (190.64 ± 21.04 days old; 28.18 ± 2.72 kg) Yucatan swine were used. Sixty-eight animals received a closed-head, accelerative TBI followed by removal of approximately 40% of circulating blood volume. Animals were then intravenously administered EE-3-SO4 formulated in the vehicle at 5.0 mg/mL (dosed at 0.2 mL/kg) or Placebo (0.45% sodium chloride solution) via a continuous pump (0.2 mL/kg over 5 min). Twelve swine were included as uninjured Shams to further characterize model pathology and replicate previous findings. All animals were monitored for up to 5 h in the absence of any other life-saving measures (e.g., mechanical ventilation, fluid resuscitation).

Results

A comparison of Placebo-treated relative to Sham animals indicated evidence of acidosis, decreased arterial pressure, increased heart rate, diffuse axonal injury and blood–brain barrier breach. The percentage of animals surviving to 295 min post-injury was significantly higher for the EE-3-SO4 (28/31; 90.3%) relative to Placebo (24/33; 72.7%) cohort. EE-3-SO4 also restored pulse pressure more rapidly post-drug administration, but did not confer any benefits in terms of shock index. Primary blood-based measurements of neuroinflammation and blood brain breach were also null, whereas secondary measurements of diffuse axonal injury suggested a more rapid return to baseline for the EE-3-SO4 group. Survival status was associated with biological sex (female > male), as well as evidence of increased acidosis and neurotrauma independent of EE-3-SO4 or Placebo administration.

Conclusions

EE-3-SO4 is efficacious in promoting survival and more rapidly restoring cardiovascular homeostasis following polytraumatic injuries in pre-hospital environments (rural and military) in the absence of standard therapies. Poly-therapeutic approaches targeting additional mechanisms (increased hemostasis, oxygen-carrying capacity, etc.) should be considered in future studies.

Prevalence and Outcome of Acute Respiratory Distress Syndrome in Traumatic Brain Injury: A Systematic Review and Meta-Analysis

OBJECTIVES

Acute respiratory distress syndrome (ARDS) in patients with traumatic brain injury (TBI) is associated with increased mortality. Information on the prevalence of ARDS and its neurological outcome after TBI is sparse. We aimed to systematically review the prevalence, risk factors, and outcome of ARDS in TBI population.

DATA SOURCES

PubMed and four other databases (Embase, Cochrane Library, Web of Science Core Collection, and Scopus) from inception to July 6, 2020.

STUDY SELECTION

Randomized controlled trials (RCTs) and observational studies in patients older than 18 years old.

DATA EXTRACTION

Two independent reviewers extracted the data. Study quality was assessed by the Cochrane Risk of Bias tool for RCTs, the Newcastle-Ottawa Scale for cohort and case-control studies. Good neurological outcome was defined as Glasgow Outcome Scale ≥ 4. Random-effects meta-analyses were conducted to estimate pooled outcome prevalence and their 95% confidence intervals (CI).

DATA SYNTHESIS

We included 20 studies (n = 2830) with median age of 44 years (interquartile range [IQR] = 35-47, 64% male) and 79% (n = 2237) suffered severe TBI. In meta-analysis, 19% patients (95% CI = 0.13-0.27, I2 = 93%) had ARDS after TBI. The median time from TBI to ARDS was 3 days (IQR = 2-5). Overall survival at discharge for the TBI cohort was 70% (95% CI = 0.64-0.75; I2 = 85%) and good neurological outcome at any time was achieved in 31% of TBI patients (95% CI = 0.23-0.40; I2 = 88%). TBI cohort without ARDS had higher survival (67% vs. 57%, p = 0.01) and good neurological outcomes (34% vs. 23%, p = 0.02) compared to those with ARDS. We did not find any specific risk factors for developing ARDS.

CONCLUSION

In this meta-analysis, approximately one in five patients had ARDS shortly after TBI with the median time of 3 days. The presence of ARDS was associated with worse neurological outcome and mortality in TBI. Further research on prevention and intervention strategy of TBI-associated ARDS is warranted.

Prognostic factors for development of acute respiratory distress syndrome following traumatic injury - a systematic review and meta-analysis

PURPOSE

To summarise the prognostic associations between various clinical risk factors and the development of the acute respiratory distress syndrome (ARDS) following traumatic injury.

METHODS

We conducted this review in accordance with the PRISMA and CHARMS guidelines. We searched six databases from inception through December 2020. We included English language studies describing the clinical risk factors associated with the development of post-traumatic ARDS, as defined by either the American-European Consensus Conference or the Berlin definition. We pooled adjusted odds ratios for prognostic factors using the random effects method. We assessed risk of bias using the QUIPS tool and certainty of findings using GRADE methodology.

RESULTS

We included 39 studies involving 5 350 927 patients. We identified the amount of crystalloid resuscitation as a potentially modifiable prognostic factor associated with the development of post-traumatic ARDS (adjusted odds ratio [aOR] 1.19 for each additional liter of crystalloid administered within first 6 h after injury, 95% CI 1.15 to 1.24, high certainty). Non-modifiable prognostic factors with a moderate or high certainty of association with post-traumatic ARDS included increasing age, non-Hispanic white race, blunt mechanism of injury, presence of head injury, pulmonary contusion, or rib fracture; and increasing chest injury severity.

CONCLUSION

We identified one important modifiable factor, the amount of crystalloid resuscitation within the first 24 h of injury, and several non-modifiable factors associated with development of post-traumatic ARDS. This information should support the judicious use of crystalloid resuscitation in trauma patients and may inform the development of a risk-stratification tools.

Possible Predictive Factor of Acute Respiratory Distress Syndrome Development After Mild Traumatic Brain Injury: A Single Rural Trauma Center Preliminary Study

Introduction Acute respiratory distress syndrome (ARDS) after mild traumatic brain injury (TBI) can be associated with significant morbidity and mortality. This study aimed to evaluate the potential predictive factors of ARDS development following mild TBI in trauma patients. Methods A retrospective chart review was done for adult trauma patients with mild TBI (GCS 13-15) requiring admission at our center from 2012 to 2020. Linear regression analysis and chi-square test were utilized to identify independent predictors of the association with ARDS in adults with mild TBI.  Results A total of 784 mild TBI patients were admitted during the time of interest; 34 patients developed ARDS during their index hospitalization. Patients who had ARDS were more likely to have acute kidney injury (AKI; p < 0.0001), sepsis (p < 0.01), rib fractures (p < 0.05), use of anticoagulants (p < 0.001), deep vein thrombosis (p < 0.001), transfusion during the first 4four hours upon admission (p = 0.01), intravenous fluid (IVF) resuscitation during the first four hours (p <0.05), the first eight hours (p = 0.01), the first 12 hours (p = 0.03), and intubation upon the admission (p < 0.0001). ARDS associated with mild TBI demonstrated a statistically significant increase in mortality during the index hospitalization (p < 0.0001). Conclusion ARDS after mild TBI can be associated with significant morbidity and mortality. Key risk factors identified include AKI, sepsis, anticoagulant use, deep vein thrombosis (DVT), transfusion in the first four hours, IVF resuscitation in the first four, eight, and 12 hours, and intubation upon admission.

Bilateral femoral shaft fracture in polytrauma patients: Can intramedullary nailing be done on an emergency basis?

INTRODUCTION

Whether damage control orthopedics (DCO) or early total care (ETC) is the best way to treat polytrauma patients who have suffered a bilateral femoral shaft fracture remains unanswered. The aim of this study was to evaluate the morbidity of bilateral femur fractures treated by simultaneous intramedullary (IM) nailing according to ETC principles.

MATERIALS AND METHODS

This retrospective single-centre study included all polytrauma patients who had suffered a femoral shaft fracture and were treated at our level I trauma centre. Demographic data, associated lesions, injury severity score (ISS) and occurrence of acute respiratory distress syndrome (ARDS) were collected prospectively in our trauma database. Unilateral fractures (UF) were compared to bilateral fractures (BF). The risk of ARDS was evaluated by multivariate logistic regression.

RESULTS

Between 2010 and 2019, 176 UF (88%) and 25 BF (12%) were included. Patients with BF had a higher ISS (36 vs. 25, p<0.001) and more brain injuries (44% vs. 15%, p=0.001) than patients with a UF. More blood transfusions were done in BF than UF (4.0 vs. 1.6 units, p=0.002). The incidence of ARDS was higher in BF patients than UF (36% vs. 4%) with longer stay in intensive care (18 vs. 12 days, p=0.02) and in the hospital (32 vs. 23 days, p=0.006). There were no deaths in either group. The risk of ARDS was correlated to ISS, but not to bilaterality.

DISCUSSION

Studies on DCO and ETC report similar mortality and ARDS rates for BF. ISS appears to determine the postoperative morbidity irrespective of how the patients are managed. In contrast with DCO, perioperative intensive care has a predominant role in ETC, allowing early definitive fixation of fractures, even in severely injured patients.

CONCLUSION

Bilateral femoral shaft fractures are a sign of severe trauma leading to high postoperative morbidity. The patient is likely to have concomitant severe injuries. Simultaneous ECM can be done emergently providing appropriate perioperative intensive care management.

LEVEL OF EVIDENCE

IV; retrospective study.

The effects of human prothrombin complex concentrate on hemorrhagic shock-induced lung injury in rats: Implications for testing human blood products in rodents

BACKGROUND

Hemorrhagic shock (HS) and trauma can result in an endotheliopathy of trauma, characterized by endothelial compromise, inflammation, and aberrant coagulation. Kcentra, a prothrombin concentrate, has been demonstrated to mitigate pulmonary vascular leak in a murine model of HS. We investigated the effects of Kcentra in a rat model of HS, to achieve physiologic endpoints of relevance.

METHODS

Rats subjected to a grade intravenous splenic injury and controlled hemorrhage for 60 minutes were resuscitated with shed volumes of (1) Lactated Ringer's (LR) solution, (2) LR + 20 IU/kg Kcentra, (3) LR + 50 IU/kg Kcentra, (4) rat fresh frozen plasma (RFFP), or (5) human fresh frozen plasma (HFFP). Blood was harvested for monitoring metabolic and coagulation function. Rat lungs were evaluated for lung injury and permeability.

RESULTS

Animals resuscitated with LR displayed a significant increase in pulmonary vascular permeability (sham, 407.9 ± 122.4; shock + LR, 2040 ± 1462). Resuscitation with RFFP (606.5 ± 169.3) reduced leak; however, treatment with Kcentra (HS + Kcentra [20 IU/kg]: 1792 ± 903.4, HS + Kcentra [50 IU/kg]: 1876 ± 1103), and HFFP (1450 ± 533.2) had no significant effect on permeability. Kcentra modestly altered clotting parameters. Metabolic measures, such as lactate, pH, and base deficit, were restored to baseline levels by both RFFP and HFFP, but not Kcentra or LR.

CONCLUSION

Kcentra did not alter pulmonary vascular permeability, but modestly increased clotting potential in injured rats. This suggests that there may be a xenogenic reaction of human products in rats and that the effects of Kcentra on vascular stability may be distinct from its ability to modulate clotting. Our data indicate that the species chosen and utilized for in vivo preclinical testing of human derived blood products is of critical importance in determining their efficacy in animal models and is the primary impetus to communicate these results.

Hyperventilation in Adult TBI Patients: How to Approach It?

Hyperventilation is a commonly used therapy to treat intracranial hypertension (ICTH) in traumatic brain injury patients (TBI). Hyperventilation promotes hypocapnia, which causes vasoconstriction in the cerebral arterioles and thus reduces cerebral blood flow and, to a lesser extent, cerebral blood volume effectively, decreasing temporarily intracranial pressure. However, hyperventilation can have serious systemic and cerebral deleterious effects, such as ventilator-induced lung injury or cerebral ischemia. The routine use of this therapy is therefore not recommended. Conversely, in specific conditions, such as refractory ICHT and imminent brain herniation, it can be an effective life-saving rescue therapy. The aim of this review is to describe the impact of hyperventilation on extra-cerebral organs and cerebral hemodynamics or metabolism, as well as to discuss the side effects and how to implement it to manage TBI patients.

The impact of non-neurological organ dysfunction on outcomes in severe isolated traumatic brain injury

INTRODUCTION

Organ dysfunction following traumatic brain injury (TBI) is common and has been associated with unpredictable outcomes. The aim of our study is to describe the incidence of non-neurological organ dysfunction (NNOD) and its impact on outcomes in patients with severe TBI admitted to our intensive care unit (ICU).

METHODS

We performed a 3-year (2015-2017) review of our Level 1 trauma center's prospectively maintained TBI database and included all adult (age ≥18y) patients with isolated severe TBI (head abbreviated injury severity (AIS) ≥3 and other AIS <3) and an ICU stay >48 hours. Organ dysfunction (OD) was measured by multiple organ dysfunction scores. Organ system failure was defined as a non-neurological component score of ≥3 on any day during the ICU stay. Outcomes measured were the incidence of NNOD and its effect on outcomes. Multivariate regression analysis was performed.

RESULTS

A total of 285 patients were included. The mean age was 48 ± 22 years, 72% were males, median [IQR] Glasgow Coma Scale (GCS) was 8[5-10], and median Injury Severity Score (ISS) was 17[10-26]. Epidural hematoma was the most common intracranial hemorrhage (49%) followed by subdural hematoma (46%). The overall incidence of NNOD was 33%, with the most common dysfunctional organ system being the respiratory (23%) followed by the cardiovascular (12%) and hepatic system (8%). The overall in-hospital mortality rate was 19% (NNOD:36% vs. No-NNOD:9%, p< 0.01). On regression analysis, NNOD was associated with higher in-hospital mortality (aOR: 2.0 [1.6-2.7]), discharge to skilled nursing facility (SNF) (aOR: 1.8 [1.4-2.2]), and Glasgow Outcome Scale-Extended (GOS-E) ≤4 (OR: 1.7 [1.3-2.3]) and p-values <0.01.

CONCLUSION

One in every three isolated severe TBI patients develop NNOD. NNOD is independently associated with worse outcomes. Understanding the mechanisms associated with NNOD in the setting of TBI may promote prevention practices and improve outcomes in TBI.

LEVEL OF EVIDENCE

Prognostic, level III.

Intracranial-to-central venous pressure gap predicts the responsiveness of intracranial pressure to PEEP in patients with traumatic brain injury: a prospective cohort study

BACKGROUND

Mechanical ventilation (MV) with positive end-expiratory pressure (PEEP) is commonly applied in patients with severe traumatic brain injury (sTBI). However, the individual responsiveness of intracranial pressure (ICP) to PEEP varies. Thus, identifying an indicator detecting ICP responsiveness to PEEP is of great significance. As central venous pressure (CVP) could act as an intermediary to transduce pressure from PEEP to ICP, we developed a new indicator, P_ICGap, representing the gap between baseline ICP and baseline CVP. The aim of the current study was to explore the relationship between P_ICGap and ICP responsiveness to PEEP.

METHODS

A total of 112 patients with sTBI undergoing MV were enrolled in this prospective cohort study. ICP, CVP, cerebral perfusion pressure (CPP), static compliance of the respiratory system (Cst), and end-tidal carbon dioxide pressure (PetCO₂) were recorded at the initial (3 cmH₂O) and adjusted (15 cmH₂O) levels of PEEP. P_ICGap was assessed as baseline ICP - baseline CVP (when PEEP = 3 cmH₂O). The patients were classified into the ICP responder and non-responder groups based on whether ICP increment with PEEP adjusted from 3 cmH₂O to 15 cmH₂O was greater than 20% of baseline ICP. The above parameters were compared between the two groups, and prediction of ICP responsiveness to PEEP adjustment was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

Compared with the non-responder group, the responder group had lower P_ICGap (1.63 ± 1.33 versus 6.56 ± 2.46 mmHg; p <  0.001), lower baseline ICP, and higher baseline CVP. ROC curve analysis suggested that P_ICGap was a stronger predictive indicator of ICP responsiveness to PEEP (AUC = 0.957, 95%CI 0.918-0.996; p <  0.001) compared with baseline ICP and baseline CVP, with favorable sensitivity (95.24, 95%CI 86.91-98.70%) and specificity (87.6, 95%CI 75.76-94.27%), at a cut off value of 2.5 mmHg.

CONCLUSION

The impact of PEEP on ICP depends on the gap between baseline ICP and baseline CVP, i.e. P_ICGap. In addition, P_ICGap is a potential predictor of ICP responsiveness to PEEP adjustment in patients with sTBI.

Protocol for TRAUMADORNASE: a prospective, randomized, multicentre, double-blinded, placebo-controlled clinical trial of aerosolized dornase alfa to reduce the incidence of moderate-to-severe hypoxaemia in ventilated trauma patients

Background

Acute respiratory distress syndrome continues to drive significant morbidity and mortality after severe trauma. The incidence of trauma-induced, moderate-to-severe hypoxaemia, according to the Berlin definition, could be as high as 45%. Its pathophysiology includes the release of damage-associated molecular patterns (DAMPs), which propagate tissue injuries by triggering neutrophil extracellular traps (NETs). NETs include a DNA backbone coated with cytoplasmic proteins, which drive pulmonary cytotoxic effects. The structure of NETs and many DAMPs includes double-stranded DNA, which prevents their neutralization by plasma. Dornase alfa is a US Food and Drug Administration-approved recombinant DNase, which cleaves extracellular DNA and may therefore break up the backbone of NETs and DAMPs. Aerosolized dornase alfa was shown to reduce trauma-induced lung injury in experimental models and to improve arterial oxygenation in ventilated patients.

Methods

TRAUMADORNASE will be an institution-led, multicentre, double-blinded, placebo-controlled randomized trial in ventilated trauma patients. The primary trial objective is to demonstrate a reduction in the incidence of moderate-to-severe hypoxaemia in severe trauma patients during the first 7 days from 45% to 30% by providing aerosolized dornase alfa as compared to placebo. The secondary objectives are to demonstrate an improvement in lung function and a reduction in morbidity and mortality. Randomization of 250 patients per treatment arm will be carried out through a secure, web-based system. Statistical analyses will include a descriptive step and an inferential step using fully Bayesian techniques. The study was approved by both the Agence Nationale de la Sécurité du Médicament et des Produits de Santé (ANSM, on 5 October 2018) and a National Institutional Review Board (CPP, on 6 November 2018). Participant recruitment began in March 2019. Results will be published in international peer-reviewed medical journals.

Discussion

If early administration of inhaled dornase alfa actually reduces the incidence of moderate-to-severe hypoxaemia in patients with severe trauma, this new therapeutic strategy may be easily implemented in many clinical trauma care settings. This treatment may facilitate ventilator weaning, reduce the burden of trauma-induced lung inflammation and facilitate recovery and rehabilitation in severe trauma patients.

Trial registration

ClinicalTrials.gov, NCT03368092. Registered on 11 December 2017.

Clinical Characteristics, Major Morbidity, and Mortality in Trauma-Related Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To determine the presence, central characteristics, and impact on major morbidity and mortality of trauma-related pediatric acute respiratory distress syndrome.

DESIGN

Retrospective review of a prospective trauma database.

SETTING

American College of Surgeons verified level 1 trauma center in an urban setting.

PATIENTS

Trauma patients age 0 to 18 years old inclusive.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 7,382 patients presenting within the 10-year study period, 646 met study criteria for inclusion in the analysis. Trauma-related pediatric acute respiratory distress syndrome was present in 9% of the analyzed cohort. On univariate analysis and compared with those without, trauma-related pediatric acute respiratory distress syndrome occurred more commonly among those with traumatic brain injury (77.2% vs 45.5%; p < 0.001), non-accidental trauma (28.8% vs 10.2%; p < 0.001), and an injury severity score greater than 30 (27.1% vs 3.8%; p 0.001). New or progressive multiple organ dysfunction syndrome was significantly higher in trauma-related pediatric acute respiratory distress syndrome patients (86.7% vs 10.4%; p < 0.001) as was mortality (18.3% vs 3.1%; p < 0.001) than in those without. The presence of trauma-related pediatric acute respiratory distress syndrome (odds ratio, 6.98; 95% CI, 2.95-16.5; p < 0.001), younger age (odds ratio, 0.93; 95% CI, 0.87-0.99; p = 0.038), and worse injury severity (odds ratio, 1.19; 95% CI, 1.14-1.24; p < 0.001) were all independent statistical predictors of new or progressive multiple organ dysfunction syndrome in this retrospective cohort. Mortality in patients without trauma-related pediatric acute respiratory distress syndrome increased with increasing injury severity, whereas mortality in patients with trauma-related pediatric acute respiratory distress syndrome was the same regardless of injury severity. On multivariable regression analysis, while age and injury severity were independent statistical predictors of mortality, trauma-related pediatric acute respiratory distress syndrome was not (odds ratio, 2.35; 95% CI, 0.88-6.28; p = 0.087).

CONCLUSIONS

Pediatric acute respiratory distress syndrome is present in the pediatric trauma population. Trauma-related pediatric acute respiratory distress syndrome is associated with eight times the organ dysfunction and five times the mortality compared with patients without trauma-related pediatric acute respiratory distress syndrome, yet research in this area is lacking. Further prospective, mechanistic evaluations are essential to understand why these patients are at risk and how to effectively intervene to improve outcomes.

It's About Time: Transfusion effects on postinjury platelet aggregation over time

BACKGROUND

Impaired postinjury platelet aggregation is common, but the effect of transfusion on this remains unclear. Data suggest that following injury platelet transfusion may not correct impaired platelet aggregation, and impaired platelet aggregation may not predict the need for platelet transfusion. We sought to further investigate platelet aggregation responses to transfusions, using regression statistics to isolate the independent effects of transfusions given in discrete time intervals from injury on both immediate and longitudinal platelet aggregation. We hypothesized that platelet aggregation response to platelet transfusion increases over time from injury.

METHODS

Serial (0-96 hours) blood samples were collected from 248 trauma patients. Platelet aggregation was assessed in vitro with impedance aggregometry stimulated by adenosine diphosphate, collagen, and thrombin receptor-activating peptide-6. Using regression, transfusion exposure was modeled against platelet aggregation at each subsequent timepoint and adjusted for confounders (Injury Severity Score, international normalized ratio (INR), base deficit, platelet count, and interval transfusions). The expected change in platelet aggregation at each timepoint under the intervention of transfusion exposure was calculated and compared with the observed platelet aggregation.

RESULTS

The 248 patients analyzed were severely injured (Injury Severity Score, 21 ± 19), with normal platelet counts (mean, 268 × 10/L ± 90), and 62% were transfused in 24 hours. The independent effect of transfusions on subsequent platelet aggregation over time was modeled with observed platelet aggregation under hypothetical treatment of one unit transfusion of blood, plasma, or platelets. Platelet transfusions had increasing expected effects on subsequent platelet aggregation over time, with the maximal expected effect occurring late (4-5 days from injury).

CONCLUSION

Controversy exists on whether transfusions improve impaired postinjury platelet aggregation. Using regression modeling, we identified that expected transfusion effects on subsequent platelet aggregation are maximal with platelet transfusion given late after injury. This is critical for tailored resuscitation, identifying a potential early period of resistance to platelet transfusion that resolves by 96 hours.

LEVEL OF EVIDENCE

Therapeutic, level V.

Neural-respiratory inflammasome axis in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality. Approximately 20-25% of TBI subjects develop Acute Lung Injury (ALI), but the pathomechanisms of TBI-induced ALI remain poorly defined. Currently, mechanical ventilation is the only therapeutic intervention for TBI-induced lung injury. Our recent studies have shown that the inflammasome plays an important role in the systemic inflammatory response leading to lung injury-post TBI. Here, we outline the role of the extracellular vesicle (EV)-mediated inflammasome signaling in the etiology of TBI-induced ALI. Furthermore, we evaluate the efficacy of a low molecular weight heparin (Enoxaparin, a blocker of EV uptake) and a monoclonal antibody against apoptosis speck-like staining protein containing a caspase recruitment domain (anti-ASC) as therapeutics for TBI-induced lung injury. We demonstate that activation of an EV-mediated Neural-Respiratory Inflammasome Axis plays an essential role in TBI-induced lung injury and disruption of this axis has therapeutic potential as a treatment strategy.

Impact of Accidental Hypothermia on Pulmonary Complications in Multiply Injured Patients With Blunt Chest Trauma - A Matched-pair Analysis

BACKGROUND/AIM

Blunt chest trauma is one of the major injuries in multiply injured patients and is associated with an increased risk of acute respiratory distress syndrome (ARDS) and ventilator-associated pneumonia (VAP). Accidental hypothermia is a common accompaniment of multiply injured patients. The objective of this study was to analyze the influence of accidental hypothermia on pulmonary complications in multiply injured patients with blunt chest trauma.

PATIENTS AND METHODS

Multiply injured patients [injury severity score (ISS) ≥16] with severe blunt chest trauma [abbreviated injury scale of the chest (AISchest) ≥3] were analyzed. Hypothermia was defined as body core temperature <35°C. The primary endpoint was the development of ARDS and VAP. Propensity score matching was performed.

RESULTS

Data were analyzed for 238 patients, with a median ISS of 26 (interquartile range=12). A total of 67 patients (28%) were hypothermic on admission. Hypothermic patients were injured more severely (median ISS 34 vs. 24, p<0.001) and had a higher transfusion requirement (p<0.001). Their mortality rate was consequently increased (10% vs. 1%, p=0.002); After propensity score matching, the mortality rate was still higher (10% vs. 2%, p=0.046). However, hypothermia was not an independent predictor of mortality. Hypothermic patients had to be ventilated longer (p=0.02). However, there were no differences in occurrence of ARDS and VAP. Hypothermia was not identified as an independent predictor of ARDS and VAP.

CONCLUSION

Among multiply injured patients with severe blunt chest trauma, accidental hypothermia is not an independent predictor of ARDS and VAP and is more likely to be an accompaniment of injury severity and hemorrhage.

Current state of transfusion in traumatic brain injury and associated coagulopathy

Traumatic brain injury (TBI)-induced coagulopathy has long been recognized as a significant risk for poor outcomes in patients with TBI, but its pathogenesis remains poorly understood. As a result, current treatment options for the condition are limited and ineffective. The lack of information is most significant for the impact of blood transfusions on patients with isolated TBI and in the absence of confounding influences from trauma to the body and limbs and the resultant hemorrhagic shock. Here we discuss recent progress in understanding the pathogenesis of TBI-induced coagulopathy and the current state of blood transfusions for patients with TBI and associated coagulopathy.

Agreement Between Arterial Carbon Dioxide Levels With End-Tidal Carbon Dioxide Levels and Associated Factors in Children Hospitalized With Traumatic Brain Injury

IMPORTANCE

Alterations in the partial pressure of carbon dioxide, arterial (Paco2) can affect cerebral perfusion after traumatic brain injury. End-tidal carbon dioxide (EtCO2) monitoring is a noninvasive tool used to estimate Paco2 values.

OBJECTIVE

To examine the agreement between Paco2 and EtCO2 and associated factors in children with traumatic brain injury.

DESIGN, SETTING, AND PARTICIPANTS

A secondary analysis was conducted using data from a prospective cohort study of 137 patients younger than 18 years with traumatic brain injury who were admitted to the pediatric intensive care unit of a level I trauma center between May 1, 2011, and July 31, 2017. Analysis was performed from December 17, 2018, to January 10, 2019.

MAIN OUTCOMES AND MEASURES

The closest EtCO2 value obtained within 30 minutes of a Paco2 value and the closest systolic blood pressure value obtained within 60 minutes prior to a Paco2 value during the first 24 hours after admission were recorded. The main outcome of Paco2-EtCO2 agreement was defined as Paco2 between 0 and 5 mm Hg greater than the paired EtCO2 value, and it was determined using Bland-Altman analysis, Passing and Bablok regression, and the Pearson correlation coefficient. Multivariable regression models determined which factors were associated with agreement.

RESULTS

The analysis included 137 patients (34 girls and 103 boys; mean [SD] age, 10.0 [6.3] years) and 445 paired Paco2-EtCO2 data points. On average, Paco2 was 2.7 mm Hg (95% limits of agreement, -11.3 to 16.7) higher than EtCO2. Overall, 187 of all Paco2-EtCO2 pairs (42.0%) agreed. There was larger variation in the Paco2-EtCO2 difference during the first 8 hours compared with 9 to 24 hours after admission to the pediatric intensive care unit. Development of pediatric acute respiratory distress syndrome within 24 hours of admission was associated with a lower likelihood of Paco2-EtCO2 agreement (adjusted odds ratio, 0.20; 95% CI, 0.08-0.51) compared with no development of pediatric acute respiratory distress syndrome. A diagnosis of pediatric acute respiratory distress syndrome 1 to 7 days after admission was associated with a larger first-day Paco2-EtCO2 difference compared with those who never developed pediatric acute respiratory distress syndrome (mean [SD] difference, 4.48 [3.70] vs 0.46 [5.50] mm Hg).

CONCLUSIONS AND RELEVANCE

In this study of pediatric traumatic brain injury, Paco2-EtCO2 agreement was low, especially among patients with pediatric acute respiratory distress syndrome. Low Paco2-EtCO2 agreement early in hospitalization may be associated with future development of pediatric acute respiratory distress syndrome. Data on EtCO2 should not be substituted for data on Paco2 during the first 24 hours.

Pediatric trauma-associated acute respiratory distress syndrome: Incidence, risk factors, and outcomes

BACKGROUND/PURPOSE

Acute Respiratory Distress Syndrome (ARDS) results in significant morbidity and mortality in pediatric trauma victims. The objective of this study was to determine risk factors and outcomes specifically related to pediatric trauma-associated ARDS (PT-ARDS).

METHODS

A retrospective cohort (2007-2014) of children ≤18 years old from the American College of Surgeons National Trauma Data Bank (NTDB) was used to analyze incidence, risk factors, and outcomes related to PT-ARDS.

RESULTS

PT-ARDS was identified in 0.5% (2660/488,381) of the analysis cohort, with an associated mortality of 18.6% (494/2660). Mortality in patients with PT-ARDS most commonly occurred in the first week after injury. Risk factors associated with the development of PTARDS included nonaccidental trauma, near drowning, severe injury (AIS ≥ 3) to the head or chest, pneumonia, sepsis, thoracotomy, laparotomy, transfusion, and total parenteral nutrition use. After adjustment for age, injury complexity, injury mechanism, and physiologic variables, PT-ARDS was found to be independently associated with higher mortality (adjusted OR 1.33, 95% CI 1.18-1.51, p < 0.001).

CONCLUSIONS

PT-ARDS is a rare complication in pediatric trauma patients, but is associated with substantial mortality within 7 days of injury. Recognition and initiation of lung-protective measures early in the postinjury course may represent the best opportunity to change outcomes.

LEVEL OF EVIDENCE

Level 3 - Epidemiologic.

The Transition Trajectory for the Patient with a Traumatic Brain Injury

The trajectory status of patients with mild, moderate, and severe traumatic brain injury from emergency room evaluation, through acute care (intensive care if severe) and discharge is discussed. Additional considerations for elderly population and common complications associated with severe traumatic brain injury are also covered.

Human Lung Cell Pyroptosis Following Traumatic Brain Injury

Approximately 30% of traumatic brain injured patients suffer from acute lung injury or acute respiratory distress syndrome. Our previous work revealed that extracellular vesicle (EV)-mediated inflammasome signaling plays a crucial role in the pathophysiology of traumatic brain injury (TBI)-induced lung injury. Here, serum-derived EVs from severe TBI patients were analyzed for particle size, concentration, origin, and levels of the inflammasome component, an apoptosis-associated speck-like protein containing a caspase-recruiting domain (ASC). Serum ASC levels were analyzed from EV obtained from patients that presented lung injury after TBI and compared them to EV obtained from patients that did not show any signs of lung injury. EVs were co-cultured with lung human microvascular endothelial cells (HMVEC-L) to evaluate inflammasome activation and endothelial cell pyroptosis. TBI patients had a significant increase in the number of serum-derived EVs and levels of ASC. Severe TBI patients with lung injury had a significantly higher level of ASC in serum and serum-derived EVs compared to individuals without lung injury. Only EVs isolated from head trauma patients with gunshot wounds were of neural origin. Delivery of serum-derived EVs to HMVEC-L activated the inflammasome and resulted in endothelial cell pyroptosis. Thus, serum-derived EVs and inflammasome proteins play a critical role in the pathogenesis of TBI-induced lung injury, supporting activation of an EV-mediated neural-respiratory inflammasome axis in TBI-induced lung injury.

Comparison of two simple models for prediction of short term mortality in patients after severe traumatic brain injury

INTRODUCTION

The subscale motor score of Glasgow Coma Scale (msGCS) and the Abbreviated Injury Score of head region (HAIS) are validated prognostic factors in traumatic brain injury (TBI). The aim was to compare the prognostic performance of a HAIS-based prediction model including HAIS, pupil reactivity and age, and the reference prediction model including msGCS in emergency department (ED), pupil reactivity and age.

METHODS

Secondary analysis of a prospective epidemiological study including patients after severe TBI (HAIS > 3) with follow-up from the time of accident until 14 days or earlier death was performed in Switzerland. Performance of prediction, based on accuracy of discrimination [area under the receiver-operating curve (AUROC)], calibration (Hosmer-Lemeshow test) and validity (bootstrapping with 2000 repetitions to correct) for optimism of the two prediction models were investigated. A non-inferiority approach was performed and an a priori threshold for important differences was established.

RESULTS

The cohort included 808 patients [median age 56 {inter-quartile range (IQR) 33-71}, median motor part of GCS in ED 1 (1-6), abnormal pupil reactivity 29.0%] with a death rate of 29.7% at 14 days. The accuracy of discrimination was similar (AUROC HAIS-based prediction model: 0.839; AUROC msGCS-based prediction model: 0.826, difference of the 2 AUROC 0.013 (-0.007 to 0.037). A similar calibration was observed (Hosmer-Lemeshow X² 11.64, p = 0.168 vs. Hosmer-Lemeshow X² 8.66, p = 0.372). Internal validity of HAIS-based prediction model was high (optimism corrected AUROC: 0.837).

CONCLUSIONS

Performance of prediction for short-term mortality after severe TBI with HAIS-based prediction model was non-inferior to reference prediction model using msGCS as predictor.

Complications and Mortality Among Correctly Triaged and Undertriaged Severely Injured Older Adults With Traumatic Brain Injuries

Determining differences in clinical outcomes of older adults treated at trauma centers (TCs) and nontrauma centers (NTCs) is imperative considering their persistent undertriage and the projected costs of fixing the problem. This study compared the incidence and predictors of complications and mortality among brain-injured older adults treated at TCs and NTCs. This secondary analysis of New York inpatient data included patients aged 55+ years, primary brain injury diagnosis, and acute care hospital admission. Interfacility transfers and nontraumatic brain injuries were excluded. International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes identified complications and mortality. Injury severity was determined by mapping ICD-9-CM diagnoses to Abbreviated Injury Scale 2005 Revision 2008 dictionary scores. A subgroup analysis of 1,594 patients with New Injury Severity Scores greater than 15 was performed to examine complications and mortality. This study included 7,138 patients who met inclusion criteria. Predictors of subgroup complications included chronic renal failure, odds ratio (OR) = 2.251 (confidence interval [CI] = 1.470-3.447), p < .001; major operating room procedure, OR = 2.349 (CI = 1.679-3.285), p < .001; number of diagnoses, OR = 1.201 (CI = 1.158-1.245), p < .001; and number of procedures, OR = 1.119 (CI = 1.077-1.162), p £ .001. Mortality predictors included age, OR = 1.031 (CI = 1.017-1.045), p < .001; preexisting coagulopathy, OR = 1.753 (C = 1.130-2.719), p = .012; number of procedures, OR = 1.122 (CI = 1.081-1.166), p < .001; acute renal failure, OR = 3.114 (CI = 1.672-5.797), p < .001; systemic inflammatory response syndrome, OR = 4.058 (CI = 1.463-11.258), p = .007; adult respiratory distress syndrome, OR = 3.179 (CI = 1.673-6.041), p < .001; and subarachnoid bleed, OR = 2.667 (CI = 1.415-5.029), p = .002. Nearly 23% of the severely/critically injured patients experienced 1 or more complications. Incidence of complications was low and comparable for TCs and NTCs. The proportion of deaths was slightly higher at TCs but not significant. The most prevalent complications carry a high mortality risk.

Commentary on the 2018 Named Series on blood-brain interfaces: Roles of neuroimmunomodulation in health and disease

This year's 2018 Named Series on blood-brain interfaces highlights the importance of brain barriers as mediators of neuroimmune communication and regulators of neurological function. The term "brain interfaces" reflects our growing understanding that brain barriers such as the blood-brain barrier (BBB) and blood-CSF barrier (BCSFB) are not only gatekeepers, but facilitators of bidirectional communication between the brain and periphery. There is also an emerging appreciation that CNS sites that are exposed to blood-borne immune molecules and cells, such as the leptomeninges and circumventricular organs, may also be considered brain interfaces with important homeostatic and pathological functions. The work featured in this Series covers novel aspects of brain interface functions that focus on mechanisms regulating barrier integrity and transporter activities, downstream consequences of neurovascular injury, peripheral organ infection/injury, and clearance of pathogenic proteins. Results of these studies have emphasized new mechanisms by which brain interface dysfunction could contribute to neuroinflammation and CNS damage in eclampsia, fetal and adult hypoxic/ischemic injury, traumatic brain injury, Helicobacter infections, acute lung injury, multiple sclerosis, and Alzheimer's disease. This body of work emphasizes that brain interfaces may themselves be important therapeutic targets for a variety of CNS diseases that are associated with immune dyshomeostasis. Future works are warranted to further investigate brain interface functions in health and disease.

Perhaps it's not the platelet: Ristocetin uncovers the potential role of von Willebrand factor in impaired platelet aggregation following traumatic brain injury

BACKGROUND

Injury to the blood-brain barrier exposes endothelium rich in von Willebrand factor (vWF), which may play a role in altered platelet aggregation following traumatic brain injury (TBI). Ristocetin is an antimicrobial substance that induces vWF-mediated aggregation of platelets. We examined these mechanisms in injured patients by measuring the aggregation response of platelets to stimulating agonists (including ristocetin) via whole-blood multiple-electrode platelet aggregometry. We hypothesized that patients with TBI have an altered platelet aggregation response to ristocetin stimulation compared with patients without TBI.

METHODS

Blood was collected from 233 trauma patients without thrombocytopenia. Platelet aggregation was assessed using multiple-electrode platelet aggregometry (Multiplate). Platelet aggregation response to stimulating agonists collagen, thrombin receptor-activating peptide 6, adenosine diphosphate, arachidonic acid, and ristocetin was measured. Factor activity was measured.

RESULTS

Of the 233 patients, 23% had TBI. There were no differences in platelet aggregation responses to any agonists between TBI and non-TBI patients except ristocetin. Platelet aggregation response to ristocetin stimulation was significantly lower in TBI patients (p = 0.03). Patients with TBI also had higher factor VIII activity (215% vs. 156%, p = 0.01). In multivariate analysis, there was a significant independent association of impaired platelet aggregation response to ristocetin stimulation with TBI (odds ratio, 3.05; p = 0.04).

CONCLUSIONS

Given the importance of platelets in hemostasis, understanding the mechanisms of impaired platelet aggregation following injury is critical. The impaired platelet aggregation response to ristocetin stimulation and corresponding increase in factor VIII activity in TBI patients may be secondary to a TBI-induced effect on vWF quantity (due to injury-driven consumption of vWF) or vWF function with resultant increase in circulating factor VIII activity (due to impaired carrying capacity of vWF). Given there are multiple known therapies for vWF deficits including desmopressin, purified and recombinant vWF, and estrogens, these lines of investigation are particularly compelling in patients with TBI and hemorrhage.

LEVEL OF EVIDENCE

Prognostic study, level II.

Amicus or Adversary Revisited: Platelets in Acute Lung Injury and Acute Respiratory Distress Syndrome

Platelets are essential cellular effectors of hemostasis and contribute to disease as circulating effectors of pathologic thrombosis. These are their most widely known biologic activities. Nevertheless, recent observations demonstrate that platelets have a much more intricate repertoire beyond these traditional functions and that they are specialized for contributions to vascular barrier integrity, organ repair, antimicrobial host defense, inflammation, and activities across the immune continuum. Paradoxically, on the basis of clinical investigations and animal models of disease, some of these newly discovered activities of platelets appear to contribute to tissue injury. Studies in the last decade indicate unique interactions of platelets and their precursor, the megakaryocyte, in the lung and implicate platelets as essential effectors in experimental acute lung injury and clinical acute respiratory distress syndrome. Additional discoveries derived from evolving work will be required to precisely define the contributions of platelets to complex subphenotypes of acute lung injury and to determine if these remarkable and versatile blood cells are therapeutic targets in acute respiratory distress syndrome.

Elevated plasma levels of TIMP-3 are associated with a higher risk of acute respiratory distress syndrome and death following severe isolated traumatic brain injury

Background:

Complications after injury, such as acute respiratory distress syndrome (ARDS), are common after traumatic brain injury (TBI) and associated with poor clinical outcomes. The mechanisms driving non-neurologic organ dysfunction after TBI are not well understood. Tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) is a regulator of matrix metalloproteinase activity, inflammation, and vascular permeability, and hence has plausibility as a biomarker for the systemic response to TBI.

Methods:

In a retrospective study of 182 patients with severe isolated TBI, we measured TIMP-3 in plasma obtained on emergency department arrival. We used non-parametric tests and logistic regression analyses to test the association of TIMP-3 with the incidence of ARDS within 8 days of admission and in-hospital mortality.

Results:

TIMP-3 was significantly higher among subjects who developed ARDS compared with those who did not (median 2810 pg/mL vs. 2260 pg/mL, p=0.008), and significantly higher among subjects who died than among those who survived to discharge (median 2960 pg/mL vs. 2080 pg/mL, p<0.001). In an unadjusted logistic regression model, for each SD increase in plasma TIMP-3, the odds of ARDS increased significantly, OR 1.5 (95% CI 1.1 to 2.1). This association was only attenuated in multivariate models, OR 1.4 (95% CI 1.0 to 2.0). In an unadjusted logistic regression model, for each SD increase in plasma TIMP-3, the odds of death increased significantly, OR 1.7 (95% CI 1.2 to 2.3). The magnitude of this association was greater in a multivariate model adjusted for markers of injury severity, OR 1.9 (95% CI 1.2 to 2.8).

Discussion:

TIMP-3 may play an important role in the biology of the systemic response to brain injury in humans. Along with clinical and demographic data, early measurements of plasma biomarkers such as TIMP-3 may help identify patients at higher risk of ARDS and death after severe isolated TBI.

Level of evidence

III.

Traumatic Brain Injury-Induced Acute Lung Injury: Evidence for Activation and Inhibition of a Neural-Respiratory-Inflammasome Axis

Approximately 20-25% of traumatic brain injury (TBI) subjects develop acute lung injury (ALI), but the pathomechanisms of TBI-induced ALI remain poorly defined. Our previous work has shown that the inflammasome plays a critical role in TBI-induced secondary pathophysiology and that inflammasome proteins are released in extracellular vesicles (EV) after TBI. Here we investigated whether EV-mediated inflammasome signaling contributed to the etiology of TBI-induced ALI. C57/BL6 male mice were subjected to controlled cortical impact (CCI), and the brains and lungs were examined for inflammasome activation and ALI at 4 and 24 h after TBI. We show that TBI releases EV containing inflammasome proteins into serum that target the lung to cause ALI, supporting activation of a neural-respiratory-inflammasome axis. Administration of a low-molecular-weight heparin (enoxaparin, a blocker of EV uptake) or treatment with a monoclonal antibody against apoptosis speck-like staining protein containing a caspase recruitment domain (anti-ASC) after adoptive transfer of EV isolated from TBI-injured mice significantly inhibited inflammasome activation in the lungs of recipient mice resulting in improved ALI scores.This axis constitutes an important arm of the innate inflammatory response in lung pathology after TBI and targeting this axis represents a novel therapeutic treatment for TBI-induced ALI.

[Topical respiratory strategies in neurocritical care]

Management of the respiratory tract and maintenance of adequate gas exchange are the basic goals of critical care. Injury to the nervous system is often accompanied by development of respiratory disorders. On the other hand, changes in the gas composition of arterial blood can cause brain damage. In addition, approaches to the patient with respiratory failure, which are used in general critical care and neurocritical care, may differ. The presented literature review is devoted to modern respiratory strategies used in neurocritical care.

Effect of Cerebral Perfusion Pressure on Acute Respiratory Distress Syndrome

BACKGROUND

Increased cerebral perfusion pressure (CPP)>70 mmHg has been associated with acute respiratory distress syndrome (ARDS) after traumatic brain injury (TBI). Since this reported association, significant changes in ventilation strategies and fluid management have been accepted as routine critical care. Recently, individualized perfusion targets using autoregulation monitoring suggest CPP titration>70 mmHg. Given these clinical advances, the association between ARDS and increased CPP requires further delineation.

OBJECTIVE

To determine the association between ARDS and increased CPP after TBI.

METHODS

We conducted a single-center historical cohort study investigating the association of increased CPP and ARDS after TBI. We collected demographic data and physiologic data for CPP, intracranial pressure, mechanical ventilation, cumulative fluid balance and delta/driving pressure (ΔP). We collected outcomes measures pertaining to duration of ventilation, intensive care unit admission length, hospitalization length and 6-month neurological outcome.

RESULTS

In total, 113 patients with severe TBI and multimodal neuromonitoring were included. In total, 16 patients (14%) developed ARDS according to the Berlin definition. There was no difference in the mean CPP during the first 7 days of admission between patients who developed ARDS (74 mmHg SD 18 vs. 73 mmHg SD 18, p=0.86) versus those who did not. Patients who developed ARDS had a higher ΔP (15 mmHg [5] vs. 12 mmHg [4], p=0.016) and lower lung compliance (35 ml/cmH2O [10] vs. 49 ml/cmH2O [18], p=0.024) versus those who did not.

CONCLUSION

We did not observe an association between increased CPP and ARDS. Patients with ARDS had higher ΔP and lower lung compliance.

Acute brain trauma, lung injury, and pneumonia: more than just altered mental status and decreased airway protection

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Even when patients survive the initial insult, there is significant morbidity and mortality secondary to subsequent pulmonary edema, acute lung injury (ALI), and nosocomial pneumonia. Whereas the relationship between TBI and secondary pulmonary complications is recognized, little is known about the mechanistic interplay of the two phenomena. Changes in mental status secondary to acute brain injury certainly impair airway- and lung-protective mechanisms. However, clinical and translational evidence suggests that more specific neuronal and cellular mechanisms contribute to impaired systemic and lung immunity that increases the risk of TBI-mediated lung injury and infection. To better understand the cellular mechanisms of that immune impairment, we review here the current clinical data that support TBI-induced impairment of systemic and lung immunity. Furthermore, we also review the animal models that attempt to reproduce human TBI. Additionally, we examine the possible role of damage-associated molecular patterns, the chlolinergic anti-inflammatory pathway, and sex dimorphism in post-TBI ALI. In the last part of the review, we discuss current treatments and future pharmacological therapies, including fever control, tracheostomy, and corticosteroids, aimed to prevent and treat pulmonary edema, ALI, and nosocomial pneumonia after TBI.

Pneumonia, Acute Respiratory Distress Syndrome, and Early Immune-Modulator Therapy

Acute respiratory distress syndrome (ARDS) is caused by infectious insults, such as pneumonia from various pathogens or related to other noninfectious events. Clinical and histopathologic characteristics are similar across severely affected patients, suggesting that a common mode of immune reaction may be involved in the immunopathogenesis of ARDS. There may be etiologic substances that have an affinity for respiratory cells and induce lung cell injury in cases of ARDS. These substances originate not only from pathogens, but also from injured host cells. At the molecular level, these substances have various sizes and biochemical characteristics, classifying them as protein substances and non-protein substances. Immune cells and immune proteins may recognize and act on these substances, including pathogenic proteins and peptides, depending upon the size and biochemical properties of the substances (this theory is known as the protein-homeostasis-system hypothesis). The severity or chronicity of ARDS depends on the amount of etiologic substances with corresponding immune reactions, the duration of the appearance of specific immune cells, or the repertoire of specific immune cells that control the substances. Therefore, treatment with early systemic immune modulators (corticosteroids and/or intravenous immunoglobulin) as soon as possible may reduce aberrant immune responses in the potential stage of ARDS.

Concise Review: Mesenchymal Stem (Stromal) Cells: Biology and Preclinical Evidence for Therapeutic Potential for Organ Dysfunction Following Trauma or Sepsis

Several experimental studies have provided evidence that bone-marrow derived mesenchymal stem (stromal) cells (MSC) may be effective in treating critically ill surgical patients who develop traumatic brain injury, acute renal failure, or the acute respiratory distress syndrome. There is also preclinical evidence that MSC may be effective in treating sepsis-induced organ failure, including evidence that MSC have antimicrobial properties. This review considers preclinical studies with direct relevance to organ failure following trauma, sepsis or major infections that apply to critically ill patients. Progress has been made in understanding the mechanisms of benefit, including MSC release of paracrine factors, transfer of mitochondria, and elaboration of exosomes and microvesicles. Regardless of how well they are designed, preclinical studies have limitations in modeling the complexity of clinical syndromes, especially in patients who are critically ill. In order to facilitate translation of the preclinical studies of MSC to critically ill patients, there will need to be more standardization regarding MSC production with a focus on culture methods and cell characterization. Finally, well designed clinical trials will be needed in critically ill patient to assess safety and efficacy. Stem Cells 2017;35:316-324.